refactor: split ConnectionFormView into SSH, SSL, and Advanced subviews

[datlechin]

Summary

Splits ConnectionFormView.swift from 1795 lines (exceeded SwiftLint error limit) into 4 focused files:

File	Lines	Purpose
ConnectionFormView.swift	1277 (-518)	Parent coordinator: General tab, footer, save/test/delete, validation
ConnectionSSHTunnelView.swift	405 (new)	SSH toggle, profiles, inline fields, TOTP, jump hosts
ConnectionSSLView.swift	90 (new)	SSL mode picker, CA cert, client cert/key
ConnectionAdvancedView.swift	152 (new)	Plugin fields, startup commands, pre-connect script, AI policy

All @State remains in the parent ConnectionFormView and is passed as @Binding to subviews. No behavior changes.

Test plan

• Create new MySQL connection — verify General tab fields work
• Enable SSH tunnel, configure profile — verify SSH tab works
• Set SSL to Verify CA, browse for cert — verify SSL tab works
• Add startup commands, set AI policy — verify Advanced tab works
• Test connection with SSH+SSL — verify test button reads all fields correctly
• Edit existing connection — verify all fields populate across tabs
• Save connection — verify all fields persist